Abstract: In order to study the seismic performance of PC base-isolated double-tower structure with a large base-floor under extremely rare earthquakes, the software ANSYS was used to carry out the finite element analysis of PC and RC base-isolated double-tower structure with a large base-floor. The floor displacement, base-floor stress distribution, other dynamic responses, and energy dissipation of the above two structures under rare and extremely rare earthquakes were compared and analyzed.The results show that compared with the RC structure, the natural vibration period and floor displacement response of the PC structure increase, while the top floor acceleration decreases. The plastic energy dissipation of the superstructure increases, and the damage is serious. Under the extremely rare earthquake, the isolation layer deformation of the two structures increases significantly, while the energy dissipation capacity decreases relatively, and the proportion of energy absorbed by the superstructure increases. Therefore, it is suggested that isolation bearing with a larger diameter should be considered in the isolation design as far as this situation is concerned. Under the extremely rare earthquake, the peak stress at the connection position of the two towers and the large base plate significantly increases, so corresponding strengthening measures should be taken in the design of the connection position of the towers.

Key words: precast structure, base isolation, multi-tower structure with a large base floor, extremely rare earthquake, seismic behavior